Use of composite articles throughout the boating, automobile, swimming pool, and bathtub industries is known in the art. Prior art composite articles include those comprising a first layer of styrenated polyester and a second layer of polyurethane. As understood by those skilled in the art, the first layer is a top layer, or show surface, of the composite article, and the second layer is a backing layer of the composite article that functions to provide support and durability to the completed composite article.
It is known in the art that during application of the first layer of styrenated polyester to a mold substrate large quantities of styrene monomers, which are considered volatile organic compounds (VOCs), are emitted and this is undesirable for environmental, health, and safety reasons. Large quantities of other VOCs, such as methyl ethyl ketone, are also typically emitted during application and cross-linking of the styrenated polyester first layers of the prior art. Emission of these other VOCs is also undesirable for environmental, health, and safety reasons. Additionally, the cross-linking of the styrenated polyester first layers typically requires extended cures including exposure to increased temperatures. It is understood in the art that such cures are costly and time consuming.
Furthermore, because the first layer of the composite article is the show surface of the composite article, the composite articles of the prior art that include styrenated polyester as the first layer are excessively brittle and suffer from cracking and chipping defects due to this excessive brittleness characteristic of styrenated polyesters. Such defects become particularly apparent during shipping, handling, transportation, and use of the composite articles.
Finally, the composite articles having styrenated polyester-based show surfaces, as well as other composite articles of the prior art, are deficient because their show surface is unstable under prolonged exposure to ultraviolet light.
Due to the many difficulties associated with the styrenated polyesters as set forth above, it is desirable to form composite articles having top layers or show surfaces formed of acrylic instead of styrenated polyester. The composite articles of the prior art having acrylic show surfaces, however, have not been able to form a suitable cohesive bond between the polyurethane backing layer and the acrylic show surface. Consequently, these composite articles have extremely poor inter-layer adhesion between the polyurethane backing layer and the acrylic show surface resulting in delamination and susceptibility to chip and other defects of the composite article.
In view of the deficiencies identified in the composite articles of the prior art, it has been desirable to provide a novel and unique UV-curable composition, composite article including the UV-curable composition, and method of forming the composite article using the UV-curable composition. Specifically, it is desirable to provide a UV-curable composition that can be applied between acrylic and polyurethane layers of a composite article to enhance bonding between these layers and to optimize certain physical properties of the composite article.